• Convertible Top Provides Cool Breeze or Refuge in Less Than 21 Seconds
• Sedan-like Noise, Vibration, Harshness Characteristics in a Hardtop Convertible
• Available F Sport Performance Accessories

The sophisticated Lexus IS 250C and IS 350C continues to blend the expressive stylishness of a hardtop convertible with the quietness and comfort of a coupe. Young at heart customers appreciate the IS convertible’s ability to quickly go from hardtop to convertible in less than 21 seconds. A fun-in-the-sun driving experience is enhanced with numerous standard and optional features including new 18-inch 5-spoke wheels with Liquid Graphite finish, leather-trimmed seating, heated and ventilated front seats and F Sport performance accessories. As it enters the 2012 model year its sporty style is complemented with the addition of a Nebula Gray Pearl exterior as it replaces Smoky Granite Mica.

Engine/Transmission/Drivetrain/Performance

The IS convertible models feature the same powertrains as the IS sedans. The IS 350C's 3.5-liter V6 delivers exhilarating performance with outstanding 306 horsepower at 6,400 rpm along with 277 lb.-ft. of torque at 4,800 rpm. The IS 250C's 2.5-liter V6 engine has a great combination of fuel efficiency and performance. The IS 250C’s V6 produces 204 horsepower at 6,400 rpm and 185 lb.-ft. of peak torque at 4,800 rpm. Both engines utilize aluminum cylinder blocks and heads, while employing dual Variable Valve Timing with intelligence (VVT-i), which controls timing on both the intake and exhaust camshafts.

A direct-type fuel-injection system provides a cooling effect in the cylinders, enabling the high compression needed to extract maximum energy from the fuel. Aside from its larger displacement, the 3.5-liter V6 differs chiefly in that it augments the direct fuel injection with port fuel injectors. In light- and medium-load conditions, these additional injectors help produce a precise burn, increasing power and efficiency, while reducing emissions. A dual exhaust system reduces backpressure at higher engine speeds. Both the IS 250C and IS 350C meet the Ultra-Low Emission Vehicle II (ULEV II) certification.

An advanced six-speed automatic transmission with steering-wheel-mounted paddle shifters is standard on the IS 350C. The IS 250C comes with either a six-speed manual transmission or the paddle-shift, six-speed automatic transmission.

Chassis/Body/Suspension/Tires/Brakes

The convertible’s three-piece hardtop provides open-air freedom with the top down through the operation of a convenient single switch. Constructed primarily of lightweight aluminum, the hardtop also provides surprising storage space but with low noise and increased security not typically found in soft-top convertibles. In addition, the top completely retracts with no elements remaining in view.

The four-link roof assembly, also made of aluminum for a lightweight design, provides smooth, even movement. Engineered to operate in an easy, efficient manner, each component is motor driven with detection switches, allowing the control unit to know their exact position at all times. In addition to the two main roof panels being constructed of light-weight aluminum, the back window’s reinforced glass construction also lends itself to reduced weight. Weather-strip changes in areas around the doors and windows ensure tight seals.

A roof-speed brake-control system decreases the roof speed especially as it approaches the end of the closing operation in either direction, ensuring an elegant and quiet movement. On models equipped with available Intuitive Park Assist (IPA), sonar sensors in the rear bumper will stop the movement of the luggage door at the start of operation if it detects an obstacle will interfere. Also, a visual warning will appear on the instrument panel if a detected obstacle may soon interfere with top operation.

When the IS convertible’s top is opened or closed, the power windows will automatically lower if in the closed position, and raise back up when the operating switch is held. Also, when the top is up, the door windows automatically lower 15 mm when the door opens, and then raise back into a fully closed position when the door closes. This ensures the doors’ clean open/close function while also maintaining a tight seal around the glass. The aluminum hardtop features an automatic front lock assembly that provides the interior security not found in soft-top convertibles. When the top is stowed in the down position in the rear of the IS convertible, the lock assembly is engaged to keep the panel in a fixed, stable position.

The IS convertible’s body structure has excellent rigidity and strength, achieved by effective structural changes and additions to the existing IS sedan platform. Areas that received modifications or additions include the rocker area; A and B pillar under structure; side collision crossmember, and upper and rear-floor crossmembers. In addition, underfloor braces were added both in the front and the rear. Additional bracing was implemented to help provide excellent handling control, ride comfort and body durability while also minimizing weight gain.

The transformation to a convertible also required reevaluation of noise, vibration and harshness (NVH) characteristics in order to meet Lexus standards. All body and chassis revisions went through extensive testing to ensure that the IS 250C and IS 350C have nearly identical NVH characteristics to the IS sedans. High-rigidity damping materials and asphalt sheets were added to help minimize vibration effects. Redesigned rear-suspension-mount bushings help reduce noise and vibration associated with the changes in body characteristics from a sedan to a convertible. Additional sound absorption and insulation materials were optimally positioned to create a quiet, comfortable cabin.

The IS convertible features two wheels. Standard 17-inch wheels utilize two multi-layered five-spoke patterns for a contemporary 10-spoke design with a clean liquid-graphite finish. Optional 18-inch wheels with all-season tires have an athletic five-spoke design with a liquid-graphite finish. Both feature the tire pressure monitor system found on the sedan models.

The IS 250C and IS 350C provide a consistent blend of driving performance and comfort in either convertible or coupe configuration. They share common double-wishbone front and multi-link rear suspension systems with the IS sport sedan models.

Engineers tuned and optimized specific features for the convertible including the double-wishbone front suspension for handling control and ride comfort; the torsional rigidity of the suspension bushings, the spring constant on the coil springs, and the shock absorber damping force; the stabilizer shape and the Electric Power Steering (EPS) gear ratio for control; the suspension bushings, coil springs and shock-damping force of the multi-link rear suspension; and a lowered rear-suspension tower with enhanced rigidity to help provide rear control, linear yaw response and improved trunk space.

Standard Vehicle Dynamics Integrated Management System (VDIM) governs all of the vehicle’s dynamic handling systems – the Anti-lock Braking System (ABS), Brake Assist (BA), Vehicle Stability Control (VSC) and Traction Control (TRAC) – employing them collectively and seamlessly to make corrections while helping provide higher dynamic capability. VDIM also interfaces with the electronic throttle control system. The IS convertible features large, ventilated four-wheel disc brakes with ABS, Electronic Brake force Distribution (EBD) and BA. The IS 350C is equipped with 13.2-inch front and 12.2-inch rear rotors with aluminum four-piston front calipers to aid in heat dissipation and stopping power and reduce unsprung weight. The IS 250C has 11.7-inch front and 12.2-inch rear rotors.

Lexus Safety and Security

Passive-safety technology begins with a number of body-structure changes integrated in the IS 250C and IS 350C to help augment strength and torsional rigidity. Seatbelt pre-tensioners and force limiters are used for the front seats, while the rear seats adopt emergency locking retractor seatbelts with an automatic locking retractor.

In addition to the dual-front airbags, the Lexus Supplemental Restraint System (SRS) for the IS convertible includes front-seat-mounted head and torso side airbags, and knee airbags for both the driver and the front passenger. The front-passenger airbag features two chambers, creating an indentation in the center impact area.

Luxury/Comfort/Convenience

The IS convertible emphasizes easy access and rear-seat comfort. In addition to front doors that are 11.8 inches longer than the IS sedans, two convenient fold-forward lock-release levers are standard on both sides of the front passenger seats, making it easier to operate from any location inside the vehicle. The passenger seat features a power slide button on the top of the seatback to ease rear seat ingress/egress. An available automatic one-touch, easy-entry power-seat mechanism provides even easier egress and ingress through quick-acting, front-seat fold-and-slide activation. The two passenger doors also have three open-stopping positions (rather than the normal two) to add convenience in various parking situations. The IS convertible also is equipped with a standard power tilt and telescoping steering column to help the driver quickly get into a comfortable position.

The IS convertible’s air conditioning system automatically adjusts for the outside temperature when the top is lowered, improving interior temperature consistency and comfort. The system adjusts the air outlets, temperature and air flow exiting the outlets. The airflow volume adjusts to outside temperature and vehicle speed, while the temperature control adjusts to outside temperature, amount of sunlight and vehicle speed. The system also includes a pollen filter and variable-control compressor.

The standard SmartAccess keyless entry and push-button-start/stop allows the driver to keep the access key fob in a pocket or purse. The standard HomeLink® programmable garage door opener also operates home security devices and other systems.

Models equipped with an automatic transmission have standard Hill-start Assist Control (HAC). HAC helps prevent the vehicle from moving backward when the driver moves their foot from brake pedal to the accelerator.

The standard Lexus Premium Audio System features a six-disc, in-dash CD changer, eight speakers, integrated SiriusXM Satellite Radio receiver (complimentary 90-day trial subscription included), Bluetooth® hands free phone capability and music streaming, and USB/iPod® connectivity. An equalizer system maintains the same acoustic field when the top is either open or closed, compensating for the natural loss of bass sounds when open. When connected to the USB port, the iPod can be controlled through the audio system or steering wheel controls, while information such as names for the artist, track and album is displayed on the headunit or navigation screen.

Luxury Options

Lexus’ Hard-Disk Drive (HDD) navigation system is available on the IS convertible and is complete with a seven-inch VGA touch-screen, and back-up camera. The navigation system also includes Voice Command casual-language voice recognition system. With Voice Command users avoid having to speak commands in a specific order. The Voice Command system also works to control many functions of the audio system, heating and air conditioning, and the navigation system.

Like all Lexus models, the IS convertible offers a Mark Levinson® Premium Surround Sound Audio system which is available in conjunction with the optional navigation system. This 12-speaker audio system features discrete 5.1 multi-channel playback with 5.1-channel speaker architecture. Its nine amplifier channels provide 270 watts total output at 0.1 percent total harmonic distortion (THD). From 20-20,000Hz, the Mark Levinson system plays conventional CDs and specially encoded DVD audio and DVD video discs, plus MP3/WMA-formatted CD-R/RW and DVD-R/RW. DVD movies can be viewed on the optional navigation system's color touch screen when the parking brake is engaged.

Optional Bi-Xenon HID headlamps with LED daytime running lamps (DRLs) are also available. The HID headlamps produce a whiter light and have a longer reach and wider distribution than conventional headlamps to help drivers see more clearly. LED DRLs help make the vehicle more visible.

The optional Intuitive Park Assist (IPA) system uses ultrasonic sensors to detect objects close to the car's front and rear bumpers, alerting the driver and showing distance to objects in the multi-information display within the speedometer. When equipped with the optional navigation system, the area behind the vehicle is shown in greater detail on the navigation screen via the backup camera.

The optional Pre-Collision System (PCS) is packaged with Dynamic Radar Cruise Control, which uses millimeter-wave radar to measure and help maintain a set distance from a vehicle traveling ahead. PCS relies on the radar sensor to detect obstacles in front of the car, and a PCS computer with sensor inputs from vehicle speed, steering angle and yaw rate is designed to determine whether a collision is unavoidable. In such a situation, PCS alerts the driver via sound and visual warnings while preemptively retracting front seat belts and pre-initializing BA so that increased braking will be applied the instant the driver depresses the pedal.

The IS convertible also offers a telematics system, Lexus Enform® with Safety Connect®, available by subscription. Safety Connect is standard on all vehicles while Lexus Enform with Safety Connect is on all vehicles equipped with the optional Navigation system. Complimentary one-year trial subscriptions are included on all purchases of new Lexus vehicles equipped with these features. The Lexus Enform and the Safety Connect response centers operate 24 hours a day, 7 days a week—every day of the year.

Lexus Enform vehicles are factory ready for subscriptions to a variety of innovative SiriusXM services including NavTraffic, NavWeather, Sports, and Stocks. SiriusXM services offer complimentary 90-day trial subscriptions and require separate SiriusXM subscriptions.

F Sport Performance Accessories Available for IS Convertible

The IS convertible F Sport Performance Accessories include performance enhancing parts such as 19-inch forged alloy wheels, brake upgrades, suspension systems, air intake, exhaust systems and more.

F Sport Performance Accessories by Lexus U.S.A. are engineered by Toyota Racing Development (TRD). When installed by an authorized dealer, the accessories are fully warranted for 12 months or for the balance of the new car warranty, whichever is greater.

Exterior Design

The IS 250C and IS 350C’s exterior design has its lineage in the IS sedan but possesses its own dynamic styling, including unique characteristics when interchanging between convertible and coupe configurations. With the exception of the hood, all other body panels have been specifically designed to blend seamlessly with the three-panel folding roof.

The convex shoulder lines distinguish the convertible’s profile, while the top-up configuration provides a sweeping cabin silhouette. With the top down, the belt-line draws up around the rear deck lid, providing a muscular look.

In the front, hood lines flow into a unique chrome grille shape, then continue down into an air inlet before flowing outward past the more distinctive elliptical fog lamp design.

The rear view features a clean, continuous design, with flowing bumper corners and a strong bumper shape that flows inward towards the exhaust. The combination taillamp clusters feature LED lights and two distinct horizontal lines that emphasize breadth, while the LED brake light integrated within the standard rear spoiler imparts a sporty impression.

The IS convertible has a best-in-class 0.29 drag coefficient (Cd). This is accomplished with the help of underbody covers below the engine (with aerodynamic steps), the full floor, and fuel-tank covers, as well as a rear-floor diffuser with vertical fin and airfoil. Other areas that contribute to the low Cd include the design shape of the outer mirrors, high-mount stop lamps, and the rear taillamps. Fender fairings before the front and rear tires reduce airflow into the wheel house, improving aero characteristics and reducing air turbulence.

Interior Design

The IS convertible interior maintains the luxury touch points associated with the IS sport sedans, while additional comfort and entertainment features provide a consistent atmosphere regardless of top configuration. Special attention was given to providing an attractive interior design when viewing the convertible externally. The door and side trim is fashioned to create continuity and continuous flow from front to back.

A four-seat configuration provides each passenger with their own comfort space, and the rear-seat console enhances the rear-passenger amenities with cup holders and storage. Soft padding on the sides of the console and the outer trim areas improve comfort. The rear headrests are retractable for improved visibility and the lever located on the front of the rear console can easily be accessed from the driver’s seat. Rear-seat comfort is enhanced by shifting seat position inboard, providing for sizeable headroom.

Ten-way adjustable power front seats, including power lumbar support are standard, and the available heated/ventilated function has a heating range that includes the shoulder areas and increases airflow in ventilation function. Front-seat backs are scaled inward, and slim, leather-trimmed seat-back pockets help to maximize rear-seat legroom.

The gauge cluster is similar to that of the IS sedan, but there are some additions on the IS convertible for style and function. The convertible features a high-contrast multi-information LCD and decreased surface-glass transmittance for enhance visibility when the top is down. The multi-information display includes status of the hardtop while in transformation, providing a bar graph showing its progress. It also shows a warning to inform the driver if the roof is not completely open/closed, a rear obstacle may impede proper open/close operation, or the open/close function is not available while the vehicle is in motion. Metallic trim around the two main gauges contribute to a premium look.

Warranty

All new Lexus vehicles come with a 48-month/50,000-mile basic limited warranty with roadside assistance for 48 months/unlimited miles. Powertrain and restraint system coverage is provided for 72 months/70,000 miles. Corrosion perforation protection is covered for 72 months, regardless of mileage.

Lexus has had a busy 2012: from a new LS to a new ES, almost every car in its lineup has been revamped and redesigned. Now the relentless march of progress casts its steely gaze upon the diminutive IS, which has been little changed since 2006. The small segment is what wins hearts and minds in the luxury car war; it's where allegiances are fought and conquered over stalwarts such as the Audi A4 and the BMW 3-series, along with newcomers such as the Cadillac ATS and competitors such as the Acura TSX and Buick Regal. Chief engineer Junichi Furuyama makes no bones about it—his team benchmarked the BMW E90—the last generation 3-series—when developing the new IS. In Lexus IS tradition, it once again looks to Munich for inspiration. This new IS, Furuyama says, will be more precise, with more communication between vehicle and driver, and an increased emphasis on driving dynamics—and more emotion, inside and out.

For starters, that means potential Lexus buyers had better get used to the "spindle" grille (their words, not ours). The IS comes with the most fearless interpretation yet: its three-dimensional grille bulges outward, wearing its Lexus badge like a medallion. The IS 250 and IS 350 models get different front bumper treatments but both are suitably aggressive.

The rest of the IS retains similar dimensions from the current model. Its GS-sourced chassis adds to the wheelbase and incidentally adds stability. Rear wheel arches are stretched to dramatic proportions. The headlights and taillights are both swoopy and angular at the corners—and in front are jagged LED-laden spars for the turn signals that are separated from the headlight body. Along with that massive Predator-faced grille, that's going to raise some eyebrows when the camouflage comes off.

Speaking of camouflage, we drove the IS on public roads as well as at an informal autocross track, becoming the sort of spy-photo targets we've always hunted down ourselves. On the road that camouflage paint manages to startle entire families in Honda Civics, sending camera phones waving, as well as baffled bystanders and dawdling middle school kids who pointed and jabbered excitedly while blocking our intersection. People in a current Lexus IS barely recognized us. Perhaps, Lexus figures, that's a good thing.

What's it like to drive?

Our autocross course in the Santa Anita Racetrack parking lot was sopping wet, a rarity for Los Angeles but a boon to show off the IS's newly christened stability and grip. We drove the 250 and 350, largely carryover powertrains from the last generation. Lexus product planners told us that a hybrid model will be available in Europe only; Americans will simply content themselves with the CT. The 250 was lively, its rear end easy to manage; it felt not only far lighter than the 350 but also nearly matched it in straight-line acceleration. In the 350, with the traction and stability control off and the reassuring safety of an empty parking lot, we had to manage its rear end delicately to preserve grip. Putting the 350 in Sport Plus mode firms up the electric power steering to hefty levels. By comparison, the 250—which doesn't get the Sport Plus option—has a noticeable center soft spot in its steering.

We ran into some issues with the transmission, which now has eight speeds in the 350; still six in the 250. (No manual will be offered.) Both upshift imperceptibly and readily, dipping into the rev limiter. But the car wouldn't allow a downshift while coming out of a corner even though there was still plenty of rev range left. It's a teething issue, undoubtedly, one that we expect to be fixed when it's ready for showtime. In various Sport modes the transmission needs to be far less conservative and far more aggressive—after all, isn't that why there's a separate Eco mode?

Do I want it?

Overall, Lexus sought to inject some of the GS into the smaller IS. The new GS is a runaway success, catching us off guard with how multi-faceted it could be. Turn the knob to Eco and you get all of the refinement you'd expect from a Lexus. Turn it to Sport, then once more for Sport Plus and you get all the loud, screaming track-day furor you'd never expect from a Lexus. We had hoped that the IS 350's Sport Plus mode, which adjusts the constantly adaptive dampers and firms up the power steering, would display this same contrast. While the steering felt more linear throughout its motions, the IS 350 remained calm, quiet and composed, with little body roll and a little too much Lexus dulling of the senses. Whereas the difference in the GS was like Jekyll and Hyde, the IS is more like Jekyll and his mildly annoyed cousin Bruce.

We expect so much out of our cars these days. We want them to cruise at 30+ mpg on the freeway all day, then rip lap times around our miniature neighborhood Nürburgring when the sun sets. We want them to be seen and heard. We want to command diverging philosophies at the push of a button—or in this case, a twist of the knob. The GS performs this with stunning alacrity. Perhaps we've been spoiled by that. But Lexus wants to imbue some of that duality into the IS. It hasn't—not yet, anyway.

Lexus promises us a more in-depth drive sometime early next year, after the IS is revealed in its final form in Detroit. Already, Furuyama promises us that between now and when it goes on sale in the first quarter there will be time to implement the changes that we suggested: transmission software tuning, for starters.

At the beginning of 2011, we rocked up to the parking lot at Southern California's Santa Anita Raceway to test the 2012 Lexus GS. This was the first sedan in the luxury brand's lineup to reset its intentions on the balance of sport and luxury. The previous GS had blanched into mute tepidity, and the new generation we drove on an autocross course and on a canyon road corrected just about everything; we liked its looks, and the Variable Gear Ratio Steering- and Adaptive Variable Suspension-equipped car moved its abilities into the realm of a true sports sedan, and it was great to drive. They absolutely nailed it.

In our review of that car, we wrote that the only other sporty Lexus was the IS, and that our favorite among its rank and file is the IS 250 with the six-speed manual. Specifically, we called it "a spirited little weakling of a car." Down on power but also on weight, it rewarded commitment and skill – it didn't have the gumption to compensate for missed shifts and bad lines, and because it was so easy to get wrong, the momentum carried through right to the smiles when you got it right.

Yet no one was ever seriously comparing the IS – Lexus' third-best-selling car – to the BMW 3 Series, and for Lexus that was a problem. You can't have your entry-level sports sedan omitted entirely from the conversation. So now, finally, it is time for the IS to get its dip into Lexus' spindle-grille-and-F-Sport-performance bath.

The aim is high: Chief Engineer Junichi Furuyama said he wanted the IS to be "the most fun to drive in the segment." That was reinforced throughout the presentation and the day with statements that the new IS should react "faithfully to even slight inputs" and that it should "respond to the driver's will." The idea with this model is to build a link from the LFA, down through the IS F, to this F Sport model.

These are goals that are hard enough in light of how cars are growing in size and weight, in general. On top of that, Lexus has to work around the ideas of luxury and refinement that any mention of the brand brings with it. Easy (well, easier) to do when you're charging LFA money, much harder when buyers are checking the bottom line and lease rates carefully. And one only needs to look at where the 3 Series has gone to see how weak the word "sport" has gotten in the phrase "sport sedan."

The next generation IS 250 and IS 350 F Sports were benchmarked against the previous-generation 3 Series M Sport, targeting its driving dynamics, feedback and fun-to-drive factor. While buyers for standard cars in the segment skew female, buyers of tuned versions like F Sports and M Sports skew male, and that's the pie Lexus wants a larger piece of.

Furuyama grouped the changes to the IS into three categories: body and suspension, driver environment and powertrain. Body rigidity has been increased by using more spot welding, a process called laser screw welding, and a lot more adhesive to join body panels at all of the major cutouts – windshield and backlight, door cutouts, engine bay and wheel arches. The front suspension is stiffer by 20 percent through the use of a new front stabilizer. In back, the IS adopts the rear suspension from the GS, separating the spring and the absorber and changing the position of the toe arm. The increased body rigidity also meant they could lower the spring rates. The objective was increased rear grip, a side benefit being that with the suspension towers going more upright there is more cargo room in the trunk.

Another part from the GS used as a starting point for this IS was the steering gear. Better feedback through the wheel and more direct steering have come through refinements like a higher stroke ratio, new ball-screw structure and increased rigidity in the pinion shaft. Lexus also wanted to give drivers the sensation of a clear on-center area.

To raise its dynamic game, the new IS 350 gets the eight-speed Sport Direct Shift (SDS) automatic from the IS F that has "G-AI," programming that makes it sensitive to g-forces and will keep it from shifting during hard cornering when in Sport mode. The 350 also gets the aforementioned Variable Gear Ratio Steering (VGRS) and Adaptive Variable Suspension (AVS) from the GS.

The IS 250 has three driving modes: Eco, Normal and Sport. The IS 350 gets four, adding Sport S+ to the top end. Sport ups the throttle sensitivity, while Sport S+ 'activates' the most aggressive settings on the electric power steering, the VGRS and the AVS.

This is called the Next Generation IS, but it's the cabin and chassis changes that go the furthest. Covered in camo as these cars were, we had to use the light and shadow to make out what we could as best we could, but on the outside this is an evolution of the current design. It doesn't look noticeably bigger than it is now, but it is noticeably more expressive.

Naturally, that starts with the spindle grille in front. The F Sports will be differentiated by exterior design and tuning, and the grilles on these sedans were filled in with different treatments on the 250s and 350s at the event – a six-bar grille up top on the 250, mesh on the 350, and each wore a different lower bumper – but we were told that these differences weren't indicative of the final cars. The headlights, single-lens jobs that are cleaner in design, jut out from the line of the car instead of being contained within it. The side sills are more sculpted and get thicker as they move rearward, then twist to form a character line that runs up the front of the rear wheel arch. It doesn't appear that substantial when viewed straight-on, but when we saw the car driving into the sun you could detect the width – everything below the sill character line is in shadow. That line is met on the other side of the rear arch by a cutline that runs over the tops of the taillights. Behind the arch, another line forms a crease that runs underneath the lights. As for the lights themselves, it almost looks like the current units have been turned over and drawn out a bit more along the sides of the car. And we don't know if the rear track is wider, but the rear arches are definitely punchier.

Instead of a lip on the decklid, the deck is shaped into a spoiler in the center of the car. Below, another crease in the bodywork runs from the bottom of the rear arch up to the bottom of the bumper, creating an effect like a built-in diffuser.

Inside, the interior feels vastly different – moreso than a list of its details would indicate. The driver's hip point has dropped 20 millimeters due to the increased concavity of the seats – and concomitant increase in bolstering. Neither the roof height nor the floor height of the car have changed, but those 20 mm raise the center tunnel and the door shoulder height in relation to your position, so you feel like you're dropped much more deeply into the cabin.

The armrest starts up near the instrument panel, the inclined portion housing the window, lock and mirror switches, sliding down into a flat stretch where one's arm would go. It's a familiar setup and replaces the L-Finesse wave of the door on the current car, where the buttons are placed on a horizontal low and in front.

The vertical slabs of paneling in the current car give way to inclines. The IP doesn't rise, cliff-like, from the center tunnel; instead it slopes up and away toward the windshield and away from the driver, but it isn't canted toward the driver. A vertical feature that houses the vents divides the upper and lower parts of the dash, textured plastic and the nav screen above, hard, shiny bits below. The climate controls have been reworked with eight buttons in two rows underneath a digital temperature readout as opposed to the six buttons in one row on the current car. Beside that readout there are touch controls to adjust the temperature; slide your finger along the silver bar, up to increase the temp, down to lower it, or you can tap either end for the same function.

We were told that one of the primary reasons for rejection of the current car among shoppers is the lack of rear leg room. That has been addressed. In the new car, with the driver's seat set for a driver nearly six-feet tall, hopping in the back seat still left an inch between the closest part of the driver's seat. Leaving one's legs in the scallops of the back of the seat meant even more space. In the previous gen our knees were hard up against the driver's seatback. There is appreciably more headroom as well. And for the first time in an IS, the rear seats fold down in a 60/40 split.

The steering wheel is the same diameter but thicker. The buttons on the left spoke are for Mode, Phone and voice commands, on the right are the selector arrows and, below that, a single switch for the 'back' button and to move the F Meter. The paddles behind the wheel are also reshaped, narrower at the top.

What is the F Meter? It is the trick that will get a lot of guys' attentions. The reconfiguring dash cluster is a wide screen that houses a single bezeled gauge, that gauge being the F Meter. When the F Meter is in the middle it displays the rev counter around its rim, and in the center displays the speed, gear and supplemental information. To the left, on the screen behind, is the oil temperature, with gas and odometer readings on the right. Tap the button on the wheel to move the F Meter to the right and the single screen to the left picks up the gas and odometer reading with supplemental notices displayed in between that and the temperature above.

When it came time to put the F Meter to work, we started with an autocross. Both the IS 250 and IS 350 were fitted with 18-inch wheels shod with Bridgestone Turanzas, 225/40 R18 up front, 255/35 R18 in back on both cars. Lexus said that the IS 250 not having Sport+ was a price-point issue and would be studied over the life cycle of the car. The 350 has that eight-speed gearbox, the 250 makes do with a six-speed automatic, and both cars' engines carry over but are fitted with sound enhancers to pipe engine noise into the cabin during sporty driving.

The only hitch to the first test was the rain – LA had seen intermittent showers for days, and while the course wasn't afflicted by standing pools of water, it was thoroughly wet.

Lexus didn't give out power numbers, but the IS 250 sounds faster than it is, the cabin filling with that induction resonance. It also feels faster than before and wastes no time working itself up to a good clip, with good throttle response in Sport and more feedback from the steering even in a straight line. The body and suspension rigidity have helped this car more than the 350; driving it correctly and maintaining momentum will still (as always) bring the greatest rewards, but the added stiffness and better response to inputs give it better reflexes and give you a larger dynamic window in which to operate. In the slalom portion that needed three flicks of the wheel at speed, the current IS 250 would skitter after you finished the slalom and were straightening out, the car's chassis and traction control still trying to catch up with what just happened. There was none of that in the new IS 250. It is still best to shift gears for yourself, though, the reflexes of the six-speed not where we'd like them in a sports sedan. Nevertheless, the IS 250 is composed, supple, chuckable, and can be pivoted around corners, even when you need to adjust your line. It's fun.

The new IS 350 is a lot faster than the IS 250 – both cars would spin wheels off the line, but we were doing five to eight more mph at the end of the short run to the first corner than in the IS 250. But it's not as much fun on an autocross course, that first turn explaining why: understeer. We were told that the 3.5-liter is about 60-70 pounds heavier than the 2.5-liter, which is part of it. The car overall feels stouter and more stable, but also heftier. Lexus wouldn't divulge curb weights other than to suggest that new car is a little lighter, but the IS 350 feels like it outweighs the 250 probably by more than it actually does. You needed to do more work to get your speed and your lines right in the 350; when you didn't, you found that the car would rather keep going in a straight line.

What's more, the additional stiffness and the advanced suspension might play the wrong kind of trick with the IS 350, making it too stiff and the rear wheels almost recalcitrant. Even in the wet the rear wheels didn't want to come loose at all unless you got boneheaded, turned traction control completely off, or got into a four-wheel slide, due to the wet, coming out of a turn at just the right speed and angle. It's isn't the kind of car you can really steer with the throttle. Overall, on the autocross it felt like a BMW 5 Series trying to be a 3 Series.

On a canyon road in San Gabriel, however, both cars came to life and the speeds each car could do and the sensation of weight were the primary differences. Cutting from apex to apex, the IS 250 in Sport, the IS 350 in Sport+, each car displays creamy handling, the 350's VGRS weights up beautifully as you increase lock, the 350's cornering limits that much higher because of its AVS. Get on them hard enough to get the tires talking, both sedans provide progressive feedback as you push closer to the edges of their abilities and don't suddenly go loose or choppy – traction control might flash its assistance, but it doesn't alter or halt proceedings.

The G-AI control on the IS 350's gearbox works as long as you stay on it; let off in the middle of a turn and it shifts a couple of times while it figures out where it should be. On both cars, even when shifting manually, we wish the actual shifts happened more quickly.

Here again, though, the 350's increased weight and stiffness, along with that tauter suspension, made it much firmer. It felt like sport sedan that was compensating for its weight with added stiffness – not uncomfortable at all, just less supple than the IS 250.

When we arrived at the event, the current IS 250 with the six-speed manual was our favorite IS. When the day was over, after driving everything, the current – not the 2014 – IS 250 with the six-speed auto is still our favorite IS. Given either of the new cars, we'd take the next generation IS 250.

Admittedly, on the day it could have been oversold to us – after the presentation we were expecting a sedan with MMA-fighter reflexes that responded to our every input and was a clear contender for the most fun-to-drive car in the segment. It's a fine car. It just isn't that.

What's not in question is that the car has evolved, it is better in almost every way, and it is more engaging if not capital-F "Fun." The only reason we'd take the current generation IS 250 over the new one is because we can get a manual transmission and stay totally in control of shifting.

The IS has evolved, yet we feel it isn't quite finished evolving – dynamically there isn't as much difference as we expected between the current car and the coming car. There isn't even as much difference as we expected between driving modes – we had to check the dash to see which one we were in. If you're going to offer four driving modes, from Eco to Sport S+, when I get to the final one I'd like there to be no doubt that I'm on the limit. We'd have liked Lexus to go further to make the new IS a proper and properly dynamic sport sedan overall, and we'd like the individual parts to mesh together better.

The autocross track was wet so we can make some allowances for that, but the canyon road wasn't. We'd like to have tried the current-gen IS on the canyon as well for a better comparison, but later in the day when the autocross was dry, someone who hadn't driven all day went out in the 350 and said that the back of the car was so planted he didn't think he could get the rear wheels unstuck, then he noted the understeer. An inertia-inclined front end and a sticky back isn't where a sport sedan should be, and his comments reinforced our assessment that this isn't a sport sedan you can get to dance on a tight course with easy inputs to the steering and the throttle. He also noted the understeer. The car does much better on actual roads than in autocrosses, the 350 especially, so it's good that that's where most drivers will use them.

While there's some room for tuning, with a mid-year on-sale date the production car probably won't be much different than what we drove. Lexus nailed the GS, so we know they can do the IS right – and we'll keep hoping that they do. As for the exterior, stay tuned for the production car's skin to be revealed at the Detroit Auto Show in January.